Washing apparatus and washing method for solar panels

ABSTRACT

Disclosed is a method for cleaning solar panels by means of a washing apparatus ( 1 ) which can be displaced on the solar panel ( 2 ) and applies rinsing water to the surface of the solar panel ( 2 ) and washes the surface with the help of washing nozzles and/or brushes. The washing apparatus ( 1 ) embraces the solar panel ( 2 ) in the edge region in such a way that the washing apparatus ( 1 ) is guided in a longitudinally movable way directly on the solar panel ( 2 ).

The invention relates to a method and a device for cleaning solarpanels, by means of a washing apparatus that can be moved on the solarpanel, which applies washing water to the surface of the solar panel,using washing jets and/or brushes, and washes the surface.

Such a device is already previously known from the GermanOffenlegungsschrift DE 10 2004 036 094 A1 [examined patent published forpublic scrutiny]. The said invention relates to a washing apparatus thatis disposed on a movable carriage, in the region of a side of a solarpanel that is to be cleaned. The washing apparatus encompasses theentire channel-shaped solar panel, whereby washing jets disposed on theinner side of the washing apparatus spray washing water stored in a tankagainst the panel. In the run-off direction of the water, a capturechannel disposed below a lower edge of the panel is assigned to thewashing apparatus, in which the water that runs off over the solar panelis captured. The water captured in this manner can be collected, treatedagain, if necessary, and used again. Since the washing apparatus formedin this way can clean the solar panel only in a fixed position of thesolar panel, because of its static arrangement, this arrangement isstill subject to problems in this regard. While it is possible to usesuch an arrangement, according to the invention, at night, in otherwords when a power plant formed from the solar panels to be cleaned isout of operation, in order to clean the panels that have been broughtinto a cleaning position at that moment, cleaning would only be possibleunder the aforementioned conditions if contamination of the solar panelswere to occur during the day, as well.

Against this background, the present invention is based on the task ofcreating a washing apparatus and a corresponding washing method forsolar panels, in which cleaning is possible in simple manner andautomatically, to a great extent, in a broad pivoting range of the solarpanel.

This task is accomplished by means of a method for cleaning solarpanels, in accordance with the characteristics of the main laim, and bya washing apparatus that can be moved on a solar panel, in accordancewith the characteristics of the secondary laim 7. Other practicalembodiments of the method according to the invention can be derived fromthe dependent laims, in each instance.

According to the invention, the washing apparatus, which is equipped, onits underside, with washing jets for applying washing water to thesurface of the solar panel, and preferably with a brush assembly forcleaning same, can be set directly onto the solar panel, so that a guiderail in the area of the solar panel can be eliminated. Instead, thewashing apparatus is adapted, in terms of its shape, to the solar panel,in the region of the longitudinal edges of the solar panel, in such amanner that the washing apparatus encompasses the solar panel in theedge region, and is guided to be longitudinally displaceable, usingsuitable slide means. Such an arrangement allows the washing apparatusto hold itself on the solar panel even when the latter is tilted, andthus setting the solar panel into a precisely defined cleaning positionis not necessary. In this way, the situation is avoided that in the caseof cleaning during operating hours of the solar panel, a displacement ofthe latter out of its operation must take place; this would cause asignificant loss in efficiency.

Another advantage of this arrangement lies in the fact that a defineddistance between cleaning means and surface is produced by means movingthe washing apparatus directly on the surface to be cleaned. Thus,damage to the surface is avoided, and very efficient cleaning is madepossible.

Furthermore, the present invention improves the arrangement proposed inthe state of the art, to the effect that in addition to washing jetsdisposed on the underside of the washing apparatus, compressed air jetsare also disposed, which can develop an additional effect duringcleaning of the surface of the solar panel. In the present arrangement,this furthermore has the advantage that not only is the surface of thesolar panel freed of dirt, but also, the water in which the dirt isdissolved can be completely removed from the surface of the solar panel.This has the advantage that even very contaminated water can still beused for cleaning the solar panel, as long as it is still capable ofabsorbing dirt particles. Thus, a clearly greater absorption capacity ofthe washing water for dirt that occurs, and clearly greater efficiencyin this regard are achieved, according to the invention.

In this connection, it has particularly proven itself to equip thewashing apparatus with a so-called known sword brush. This is an endlessbelt driven by an electric motor, which is essentially configured as anendless brush by means of a corresponding bristle placement.

Accordingly, it is practical that recovery of the washing water used canalso take place, in accordance with the method according to theinvention, in that a capture device is disposed to the washing apparatuson an edge of the solar panel on the run-off side, for example a capturechannel, by way of which the washing water used can be passed back intoa tank that is carried along on the washing apparatus. The water kept onhand in the used water tank can either be used for renewed cleaning ofsolar panels, or can be removed and passed to treatment. As analternative to a capture channel into which the water is passedessentially under the effect of gravity, a suction device can beprovided, particularly for cleaning horizontally adjusted solar panels,in place of the capture channel. The partial vacuum that is necessaryfor operation of the suction device can advantageously be produced usinga compressor, which advantageously supplies the compressed air requiredfor the compressed air jets, at the same time. In this case, it ispractical to provide a water separator between suction device and intakeside of the compressor, which separator brings about separation of waterand compressed air that is produced.

It is advantageous if a drive, for example an electric motor, isassigned to the washing apparatus, by means of which the washingapparatus can be moved on the solar panel. It is furthermoreadvantageous if the washing apparatus can be used automatically, so thatindependent movement on the solar panels is made possible on the basisof the guide formed by the longitudinal edges of the solar panels aswell as the electric motor. It is possible to thread the washingapparatus on or off at solar panels positioned at the ends.

To improve the washing result, the angle position of the washing jetsand/or the compressed air jets is selected in such a manner that thejets are oriented in the direction of the water run-off to be expected.In this way, removal of the water from the surface to be cleaned isadditionally promoted. In a practical further development, the washingjets and/or compressed air jets can be adjusted in their angle position,in such a manner that each angle position of the solar panel to becleaned can be taken into consideration. It is advantageous if the anglesetting takes place automatically.

Guidance of the washing apparatus on the solar panel advantageouslytakes place by means of a plurality of wheel axles and/or roller axles,which are distributed over the lower surface of the washing apparatus,spaced apart from one another. The said wheel axles and/or roller axlesare advantageously particularly spaced so far apart from one anotherthat a space between two adjacent solar panels can be overcome in that aplurality of wheel axles and/or roller axles still engage on one solarpanel, while the foremost wheels or rollers already reach the adjacentsolar panel. Solar panels adjacent to one another are usually orientedtowards the same receiver, so that they usually also have the same angleorientation. A different angle orientation of two adjacent solar panels,which would make such a transfer impossible, therefore does not have tobe feared.

Because of different possible angle positions of the solar panels, it ispractical to also produce a lateral guide of the washing apparatus inthat lateral guide rollers are also provided in the washing apparatus,in the region of the edges of the solar panel. These lateral guiderollers have running surfaces that run essentially at a right angle tothe surface to be cleaned, and thus ensure additional guidance of thewashing apparatus on the solar panel.

In a concrete embodiment, however, the washing apparatus can also beoperated as a non-autarchic system, in that an external washing vehicleis assigned to a washing apparatus. This vehicle travels between thesolar panels, while a connection by means of cable winches betweenwashing vehicle and washing apparatus is implemented by way of boom armsof the washing apparatus or washing apparatuses assigned to the washingvehicle. The washing apparatuses can be pivoted out, by way of the boomarms, using the cable winches, and threaded onto the solar panels, andafterwards, the washing vehicle follows the washing apparatuses alongthe solar panels. In this case, supply to and disposal from the washingapparatuses takes place from the washing vehicle, whereby the washingvehicle can optionally store and supply energy and/or washing water.

The invention described above will be explained in greater detail in thefollowing, using an exemplary embodiment shown in the drawing.

This shows:

FIG. 1 a washing apparatus that is set onto a solar panel, in anisometric representation, and

FIG. 2 the washing apparatus according to FIG. 1 in a top view, from theside.

FIG. 1 shows a washing apparatus 1 for cleaning solar panels 2, which isset onto a solar panel 2. In this connection, cleaning of the solarpanel 2 can take place at different angle positions of the supportstructure 4, since the washing apparatus 1 encompasses the edges of thesolar panel 2 in clamping manner. In this connection, the washingapparatus 1 is mounted on rollers that allow movability of the washingapparatus 1 in the longitudinal direction of the solar panel 2. Thus, itis not necessary to assign a guide rail or similar guide device for thewashing apparatus 1 to the solar panel 2. Use of the washing apparatus 1can be used both on heliostats for line-focused solar-thermal powerplants, and for parabolic channels or photovoltaic systems. In eachcase, the side of the washing apparatus 1 that faces the solar panel 2is adapted, at least to a great extent, to the surface or mirror surface5 of the solar panel 2. During the course of cleaning, the washingapparatus 1 slides over the solar panel 2, whereby washing water isapplied to the mirror surface 5 of the solar panel 2 from a water tankthat is carried along with the washing apparatus 1, by way ofcorresponding washing jets, and, if necessary, additional cleaning ofthe solar panel 2 is brought about by means of brush assemblies.Cleaning of the solar panel 2 brought about in this manner isadditionally supported using compressed air jets, which also loosen dirtparticles from the mirror surface 5, for one thing, and for another inturn free the mirror surface of washing water. The washing water can bepumped back into a water tank accommodated within the housing 6 of thewashing apparatus 1, using a suction device, so that the cleaned mirrorsurface 5 is left dry, to a great extent. In this way, cleaning withrelatively contaminated water is possible, since removal of water anddirt, essentially free of residues, is guaranteed by the cleaning withcompressed air and the drying of the solar panel 2.

FIG. 2 shows the washing apparatus 1 described above in a side view,whereby the encompassing of the solar panel 2 by the washing apparatus 1particularly stands in the foreground. In the region of the side edgesof the solar panel 2, an accommodation 3 for the side edges of the solarpanel 2 is provided in the washing apparatus 1, on both sides, in eachinstance, which accommodates the edges, and in the region of whichmounting of the washing apparatus 1 on the solar panel 2 is broughtabout using rollers having different orientation. By means of additionalguide rollers, which are disposed essentially perpendicular to themirror surface 5 with their running surface, centering of the washingapparatus 1 on the solar panel 2 is brought about, and guidance of thewashing apparatus 1 is made complete. A motor is assigned to the washingapparatus 1, so that automatic cleaning of a solar panel 2 can takeplace. Cleaning of multiple solar panels 2 can take place in that thewashing apparatus 1 pushes itself beyond the end of a solar panel 2,whereby the dimensions of the washing apparatus 1, particularly the axlespacings, are selected in such a manner that there is still a hold onthe first solar panel when the second solar panel is reached. In thismanner, spaces between the solar panels 2 can be bridged, and automaticcleaning of a plurality of solar panels 2 with the arrangement accordingto the invention is made possible.

Above, a washing apparatus and a washing method for solar panels aretherefore described, in which a holding system is implemented, so thatsetting the washing apparatus directly onto the solar panels to becleaned, even without guide rails, is made possible. Furthermore, knownwashing methods for solar panels are improved to the effect that moreefficient cleaning that saves water and resources is implemented, usingcompressed air.

REFERENCE SYMBOL LIST

-   1 washing apparatus-   2 solar panel-   3 accommodation-   4 support structure-   5 mirror surface-   6 housing

1. Method for cleaning solar panels, by means of a washing apparatus (1)that can be moved on the solar panel (2), which applies washing water tothe surface of the solar panel (2), using washing jets and/or brushes,and washes the surface, wherein the washing apparatus (1) encompassesthe solar panel (2), in the edge region, in such a manner that thewashing apparatus (1) is guided, in longitudinally displaceable manner,directly on the solar panel (2).
 2. Method according to claim 1, whereinthe water applied to the surface of the solar panel (2) by the washingapparatus (1) is removed from the surface using compressed air, andpreferably using at least one brush assembly.
 3. Method according toclaim 1, wherein water applied to the surface of the solar panel (2) iscaptured using a capture device, preferably in the form of a channel. 4.Method according to claim 1, wherein the water applied to the surface ofthe solar panel (2) is suctioned off using a suction device.
 5. Methodaccording to claim 1, wherein the washing apparatus (1) is motor-drivenand can be moved on the solar panel (2), preferably automatically. 6.Method according to claim 1, wherein the washing apparatus (1) isthreaded on at one end of a solar panel (2).
 7. Washing apparatus thatcan be moved on a solar panel, for cleaning same, which has washing jetsfor application of washing water to the surface of the solar panel (2)on its side that faces the surface of the solar panel (2), wherein thewashing apparatus (1) encompasses the solar panel (2), in the edgeregion, in such a manner that the washing apparatus (1) is guided, inlongitudinally displaceable manner, directly on the solar panel (2). 8.Washing apparatus according to claim 7, wherein the washing apparatus(1) is mounted on rollers and/or wheels, at least in the edge region. 9.Washing apparatus according to claim 7, wherein the washing apparatus(1) is empowered for automatically moving along the solar panel (2), bymeans of a motor drive.
 10. Washing apparatus according to claim 7,wherein compressed air jets are assigned to the washing apparatus (1) onits side that faces the surface of the solar panel (2).
 11. Washingapparatus according to claim 7, wherein the washing apparatus (1)comprises at least one brush assembly, in such a manner that the waterapplied to the surface of the solar collector (2) by the washingapparatus (1) is removed from the surface using compressed air, andpreferably using at least one brush assembly.
 12. Washing apparatusaccording to claim 7, wherein the brush assembly is a sword brush, inwhich an endless belt guided over a deflection roller disposed at aremote location can be put into circulation by means of a drive rollerdriven by an electric motor, whereby this driven endless belt isequipped with projecting bristles on the outside, preferably over theentire length of the endless belt.
 13. Washing apparatus according toclaim 7, wherein the brush assembly is articulated on so that it canpivot.
 14. Washing apparatus according to claim 7, wherein a capturedevice, preferably in the form of a capture channel, for accommodatingthe used washing water, is assigned to the washing apparatus (1) in theregion at least of the edge of the solar panel (2) situated in therun-off direction of the washing water.
 15. Washing apparatus accordingto claim 7, wherein a suction device, particularly at least one suctionnozzle, is assigned to the washing apparatus (1), in such a manner thatthe used washing water can be removed from the surface of the solarpanel (2) using the suction device.
 16. Washing apparatus according toclaim 15, wherein the partial vacuum required for operation of thesuction device is produced using a compressor used to generatecompressed air to supply compressed air jets.
 17. Washing apparatusaccording to claim 16, wherein a water separator is provided between thesuction device and the intake side of the compressor.
 18. Washingapparatus according to claim 7, wherein the washing jets and/orcompressed air jets are set at a slant relative to the surface of thesolar panel (2), in such a manner that the water or compressed airapplied by them, respectively, is oriented in the run-off direction ofthe water.
 19. Washing apparatus according to claim 18, wherein theangle position of the washing jets and/or the compressed air jets can beadjusted, preferably automatically.
 20. Washing apparatus according toclaim 7, wherein guide rollers disposed on the sides are assigned to thewashing apparatus (1), in the region of the edges of the solar panel(2), whose running surfaces lie against the edges of the solar panel(2).
 21. Washing apparatus according to claim 7, wherein multiple,preferably at least three, wheel axles and/or roller axles are assignedto the washing apparatus (1).
 22. Washing apparatus according to claim7, wherein at least a part of the compressed air jets is disposed at theback, in the end position, in the movement direction of the washingapparatus (1).
 23. Washing apparatus according to claim 7, wherein anexternal washing vehicle is assigned to the washing apparatus (1), whichthe washing apparatus (1) is connected to by way of supply and disposallines, preferably flexible lines.
 24. Washing apparatus according toclaim 23, wherein multiple washing apparatuses (1) are assigned to onewashing vehicle.
 25. Washing apparatus according to claim 24, whereinthe washing apparatuses (1) of the washing vehicle are suspended on boomarms assigned to the washing vehicle, so that they can be pivoted andadjusted in height, using cable winches.